sis(4) flow control

[Yonghyeon PYUN]

On Tue, Jul 09, 2013 at 03:52:25PM +0200, Andreas Longwitz wrote:
> Some of my soekris boxes run with sis interfaces. Because I need
> ethernet flow control on these boxes I use the following patch (against
> 8-Stable) for some years:
> 
> --- if_sis.c.orig      2013-05-15 20:01:16.000000000 +0200
> +++ if_sis.c           2013-06-24 15:58:05.000000000 +0200
> @@ -1965,6 +1965,18 @@
>         }
>  #endif
> 
> +       if (sc->sis_type == SIS_TYPE_83815 && sc->sis_srr >= NS_SRR_16A) {
> +             if (ifp->if_flags & IFF_LINK0) {
> +                /*
> +                 * Configure Ethernet flow control for outgoing frames.
> +                 * Enable reception of 802.3x multicast pause frames.
> +                 */
> +                SIS_SETBIT(sc, NS_PCR, NS_PCR_PAUSE );
> +             } else {
> +                SIS_CLRBIT(sc, NS_PCR, NS_PCR_PAUSE );
> +             }
> +       }
> +
>         mii = device_get_softc(sc->sis_miibus);
> 
>         /* Set MAC address */
> 
> Other network drivers (eg. vr) have this functionality inside, it would
> be fine if sis learns flow control too.
> 

Hmm, does the change really make flow-control work?
I believe flow-control should be negotiated with remote link
partner so you have to announce flow-control capability to link
partner. In addition, it seems DP83815/DP83816 does not support
TX flow-control so it just honors RX pause frames.
Try attached patch and let me know how it works.
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